Set aside a day as Colour Day. On this day, each student in the class can choose his/her favourite colour and focus on it.
Each one can wear an outfit of their chosen colour to class. Her snack box, bag and stationery can match. The student can give a one-minute talk on his favourite colour — facts, details and trivia relating to the colour. One can wear unusual colors like gold, silver or bronze too.
The teacher must be a part of the celebration. You can even bring sweets of your favourite colour for everyone!